const {useState} = React

function Counter() {
  const [number, setNumber] = useState(0)
  
  const handleClick = () => {
    let temp  = number
    setNumber(++temp)
  }
  
  return (
    <div>
      {number}<br />
      <button onClick={handleClick}>+1</button>
    </div>
  )
  
}

ReactDOM.render(<Counter />, document.getElementById("root"))